Salt stress affects xylem differentiation of grey poplar (Populus x canescens).
In this study the impact of salt stress on the physiology and wood structure of the salt-sensitive Populus x canescens was investigated. Two weeks of salt stress altered wood anatomy significantly. The xylem differentiation zone was reduced and the resulting vessels exhibited reduced lumina. To understand this phenomenon, ion composition, levels of corresponding transcripts and of the stress hormone ABA were analysed. With increasing sodium and chloride concentrations, a general reduction of potassium was found in roots and shoots, but not in leaves. Consequently, the corresponding K+ channel transcripts in roots favoured K+ release. The overall osmolarity in leaves was up to fourfold higher than in roots or shoots. Therefore, adjustment of the K+/Na+ balance seemed not to be required in leaves. Sodium increased gradually from roots to shoots and then to leaves indicating that sodium storage took place first in roots, then in shoots, and finally in leaves to protect photosynthesis from salt effects as long as possible. Since leaf abscisic acid levels markedly increased, stomatal closure seemed to limit CO2 uptake. As a consequence, diminished nutrient supply to the cambium in combination with lowered shoot K+ content led to decreased vessel lumina, and a reduction of the radial cambium was observed. Thus, xylem differentiation was curtailed and the development of full size vessels was impaired.
Escalante-Pérez
María
M
Universität Würzburg, Biozentrum, Julius-Von-Sachs-Institut Für Biowissenschaften, Julius-Von-Sachs-Platz 2, 97082, Würzburg, Germany.
Lautner
Silke
S
Nehls
Uwe
U
Selle
Anita
A
Teuber
Markus
M
Schnitzler
Jörg-Peter
JP
Teichmann
Thomas
T
Fayyaz
Payam
P
Hartung
Wolfram
W
Polle
Andrea
A
Fromm
Jörg
J
Hedrich
Rainer
R
Ache
Peter
P
D000040:Abscisic Acid / Q000378:metabolism; D017360:Arabidopsis / Q000235:genetics; D001692:Biological Transport / Q000187:drug effects; D002454:Cell Differentiation / Q000187:drug effects*; D003433:Crosses, Genetic; D004602:Elements; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D008293:Malates / Q000378:metabolism; D010802:Phylogeny; D018515:Plant Leaves / Q000187:drug effects / Q000378:metabolism; D018517:Plant Roots / Q000166:cytology / Q000187:drug effects; D032107:Populus / Q000166:cytology* / Q000187:drug effects* / Q000235:genetics; D011188:Potassium / Q000378:metabolism; D015221:Potassium Channels / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012964:Sodium / Q000378:metabolism; D012965:Sodium Chloride / Q000494:pharmacology*; D013312:Stress, Physiological / Q000187:drug effects*; D014934:Wood / Q000166:cytology / Q000187:drug effects; D052584:Xylem / Q000166:cytology* / Q000187:drug effects / Q000648:ultrastructure
D004602:Elements; D008293:Malates; D015221:Potassium Channels; D012333:RNA, Messenger; D012965:Sodium Chloride; D000040:Abscisic Acid; C030298:malic acid; D012964:Sodium; D011188:Potassium